Holographic images have been placed on articles for security purposes. The need for holographic images has been increasing due to the prevalence of high-quality color copiers. Because of these high-quality color copiers, persons practiced in counterfeiting and tampering have made forged, high-quality tickets for sporting events, theater, commuter train passage and concerts. Financial loss occurs when these fraudulent tickets are sold to unwary consumers who are turned away from the gate upon detection by ticket takers, or when businesses lose revenue because of entry gained through the use of fraudulent tickets. The placing of holograms on genuine tickets or other similar substrates for use in admission discourages tampering, and makes tampering and counterfeiting more difficult and expensive, thereby reducing the financial losses to unwary consumers and businesses.
Currently, holograms are bonded to ticket blanks and other similar substrates in a heat stamping method. Particularly, holographic hot-stamp foils are obtained from commercial suppliers, including TransferPrint Foil, Inc., of East Brunswick, N.J., and Crown Roll & Leaf Company of Chicago, Ill. One side of these holographic hot-stamp foils includes a metallic layer, typically a few Angstroms thick, and the holographic image. The other side includes a heat sensitive adhesive. Preferred heat sensitive adhesives include thermoplastic polymers. This heat sensitive adhesive usually includes a filler or pigment, such as calcium carbonate or titanium dioxide, which assists in disrupting the adhesive's continuity. This disruption in continuity aids the foil in breaking along a precise edge upon transfer to the substrate.
Holograms placed onto substrates through the use of hot-stamp foils cannot be easily removed in their entireties because of the very thin and fragile nature of the foil. Part of the reason for this difficulty in removal is caused by the application conditions of the hologram onto the substrate. Particularly, the hologram is bonded to the substrate under high heat and pressure conditions. Although this technique is effective in providing a permanent, relatively tamper-proof hologram onto a substrate, the process used to apply the hologram requires specialized stamping equipment. The price of such equipment starts at around $40,000.
A further drawback of the hot-stamp technique of hologram transfer is that it employs a shaped or engraved metal slug. Each different size and image for a given hologram requires a differently shaped or engraved metal slug.
Furthermore, hot stamp foils are secured to polyester films of a thickness or gauge that does not respond adequately to the thermal transfer printer. Such foil-carrier films are generally much thicker than a thermal transfer printing ribbon. Alternatively, thermal transfer print ribbons are too thin or weak to withstand the embossing process that creates the holographic or diffractive pattern.
Accordingly, it would be desirable to devise a method of transferring a hologram onto a substrate using substantially less expensive equipment, while still providing a secure and nonremovable hologram. Moreover, it would be desirable to provide a holographic thermal transfer ribbon which enables such transfer of a hologram from a treated holographic hot-stamp foil using less expensive equipment, i.e., a thermal transfer printer.
The versatile improvement of this invention results from the employment of thermal transfer printers employing computer-generated graphics, rather than mechanical stamping slugs. Through the use of such thermal transfer printers, operators can create complex, holographic indicia. Such complex holographic indicia are more difficult to reproduce than conventionally shaped holograms and are, thus, more valuable and less susceptible to fraudulent abuse by counterfeiters.